Light source device

ABSTRACT

A light source device includes a plurality of light sources, a substrate on which the light sources are arranged, and a reflective member arranged on the substrate via an adhesive member. The reflective member defines a plurality of through holes. The light sources are respectively disposed inside the through holes in a plan view. The adhesive member is light-reflective.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. patent application Ser. No.17/172,991, filed on Feb. 10, 2021, which is a continuation applicationof U.S. patent application Ser. No. 16/811,880 filed on Mar. 6, 2020,now U.S. Pat. No. 10,948,775. This application claims priority toJapanese Patent Application No. 2019-042718, filed on Mar. 8, 2019, andJapanese Patent Application No. 2020-025979, filed on Feb. 19, 2020. Theentire disclosures of U.S. patent application Ser. Nos. 17/172,991 and16/811,800 and Japanese Patent Application Nos. 2019-042718 and2020-025979 are hereby incorporated herein by reference.

BACKGROUND

The present disclosure relates to a light source device.

Surface-emitting light source device are known as a direct-illuminationbacklight used in liquid crystal televisions, in-vehicle instruments, orthe like. An example of the surface-emitting light source devices isdescribed in Japanese Patent Publication No. 2013-25945. Such a lightsource device has frames arranged in a matrix shape, each of the frameshaving a reflective peripheral wall around a corresponding one of lightsources. This structure provides divided light-emitting regions andprevents light leakage to the outside of the regions.

SUMMARY

However, particularly in in-vehicle instruments having anunevenly-shaped plane in a plan view, the light sources are not alwaysarranged regularly at the outer periphery of the on-vehicle instruments.This may lead to unevenness of luminance in the plane. The presentdisclosure has been made in view of the above and has an object toprovide a light source device, in the case in which the light sourcedevice has an unevenly-shaped plane, having a uniform luminance in theplane.

A light source device according to one aspect includes a plurality oflight sources, a substrate on which the light sources are arranged, anda reflective member arranged on the substrate via an adhesive member.The reflective member defines a plurality of through holes. The lightsources are respectively disposed inside the through holes in a planview. The adhesive member is light-reflective.

The light source device according to certain embodiments of the presentdisclosure can provide, in the case in which the light source device hasan unevenly-shaped plane, a uniform luminance in the plane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic plan view of a light source device according toone embodiment of the present disclosure.

FIG. 1B is a schematic cross-sectional view taken along the line A-A′ inFIG. 1A.

FIG. 1C is a schematic cross-sectional view taken along the line B-B′ inFIG. 1A.

FIG. 1D is a schematic partial enlarged cross-sectional view aroundfirst walls in FIG. 1A.

FIG. 1E is a schematic exploded perspective view of the light sourcedevice according to one embodiment of the present disclosure.

FIG. 1F is a schematic cross-sectional view showing a main part of thelight source device including a portion of a member shown in FIG. 1E.

FIG. 2A is a schematic partial enlarged cross-sectional view around alight-emitting element of the light source device in FIG. 1A.

FIG. 2B is a graph illustrating a batwing light distributioncharacteristic of a light-emitting element of the light source device inFIG. 1A.

FIG. 3A is a schematic plan view of a light source device according toanother embodiment of the present disclosure.

FIG. 3B is a schematic plan view of a light source device according tostill another embodiment of the present disclosure.

FIG. 3C is a schematic plan view of a light source device according tostill another embodiment of the present disclosure.

DESCRIPTION

Embodiments of the present disclosure will be described below withreference to the accompanying drawings. The embodiments described beloware intended to embody the technical idea of the present disclosure andare not intended to limit the present disclosure to the embodimentsbelow unless specifically stated otherwise. Constitutions describedregarding an embodiment or an example are applicable to otherembodiments or examples. The sizes, positional relationships, and thelike of members shown in the drawings can be exaggerated for clarity ofdescriptions.

In the present embodiment, a light extraction surface of a light sourceof a light source device can be referred to as an upper surface or anupside. Also, unless otherwise specified, in a plan view, the centralpart of each of the light source device, a substrate, and/or areflective member can be referred to as an inner side. An opposite sideof the inner side thereof can be referred to as an outer side.

As shown in FIGS. 1A through 1F, a light source device according to oneembodiment of the present disclosure includes light sources 9, asubstrate 8 on which the light sources are arranged, and a reflectivemember 10. Such a light source device serves as a surface-emitting lightsource device. The reflective member 10 includes one or more first walls11 each surrounding a corresponding one of the light sources 9 and oneor more second walls 12 that are located outside the first walls 11 anddefine at least one opening facing outside. The reflective member 10includes first regions 11R each surrounded by the first walls 11, secondregions 12R surrounded by the second walls 12, and third regions 13Rsurrounded by the second walls 12. The second regions 12R each have atleast a half of an area of the first region 11R. The third regions 13Reach have an area less than half of the area of the first region 11R.The light source 9 is disposed in the second region 12R and not disposedin the third region 13R.

Even in the case in which the light source device has an unevenly-shapedplane, this configuration can provide a uniform luminance in the plane.

Light Source 9

The light source 9 is a light-emitting member. Examples of the lightsource 9 include a light-emitting element that emits light by itself, alight-emitting element encapsulated by a light-transmissive resin andthe like, and a surface mounted light-emitting device (LED) in which alight-emitting element is packaged. The light sources 9 are preferablyregularly arranged on the substrate 8 in parallel, for example,vertically and laterally, in columns and rows, and in a matrix shape.This configuration can provide a uniform luminance in the plane. Thatis, the light sources 9 are preferably regularly arranged in columns androws as shown in FIG. 1A. As shown in FIG. 3C, the light sources 9 canbe arranged regularly in the row direction, and in the column direction,such that each of the light sources 9 is regularly disposed in parallelto and disposed between the adjacent rows of the light sources 9, whilebeing shifted by half the length of the light source 9 in the rowdirection.

An example of the light source 9 includes a light-emitting element 7covered by an encapsulating member 5 as shown in FIG. 2A. A singlelight-emitting element 7 can be used for the light source 9.Alternatively, a plurality of light-emitting elements 7 can be used as asingle light source.

The light source 9 can have any light distribution characteristic,however, the light source 9 preferably has a wide light distribution toreduce unevenness in luminance in each region that is surrounded bywalls of the reflective member 10 that will be described later.Particularly, each light source 9 preferably has a batwing lightdistribution characteristic as shown in FIG. 2B. This can reduce theamount of light emitted directly upward from the light source 9 andbroaden light distribution of each light source, so that the broadenedlight is reflected by the reflective member 10. Accordingly, unevennessin luminance in each region that is surrounded by the walls can bereduced.

Herein, the “batwing light distribution characteristic” is defined byassuming an optical axis L to be zero degrees, and a light distributioncharacteristic having an emission intensity distribution in which theemission intensity at distribution angles at absolute values larger thanzero degrees is greater than the emission intensity at zero degree. Asshown in FIG. 2A, the “optical axis L” is defined as an axis that passesthrough the center of the light source 9 and vertically intersects witha plane configuring an upper surface of the substrate 8, which will bedescribed later.

Particularly, an example of the light source 9 having a batwing lightdistribution characteristic includes a light-emitting element 7 thatincludes a light-reflective film 6 on the upper surface of thelight-emitting element 7 as shown in FIG. 2A. This allows light emittedupward from the light-emitting element 7 to be reflected by thelight-reflective film 6 and reduces the amount of light emitted directlyupward from the light-emitting element 7. Thus, the batwing lightdistribution characteristic can be obtained. As the light-reflectivefilm 6 can be formed directly on the light-emitting element 7, theassembling of a special lens for achieving the batwing lightdistribution characteristic is not needed. This allows the light source9 to have a reduced thickness.

The light-reflective film 6 formed on the upper surface of thelight-emitting element 7 can be any of a metal film formed using silver,or copper, or a dielectric multilayer (distributed Bragg reflector: DBR)film, or a combination of these films. The light-reflective film 6preferably has incident angle dependence of reflectance for a lightemission wavelength of the light-emitting element 7. Specifically, thelight-reflective film 6 preferably has a lower reflectance with respectto a light incident in an oblique direction than a reflectance thereofwith respect to a light incident in a perpendicular direction. Thisconfiguration can inhibit unevenness in luminance directly above thelight-emitting element, and thus inhibit noticeable darkness such as adark spot directly above the light-emitting element.

The light source 9 includes, for example the light-emitting element 7mounted directly on the substrate and having a height in a range of 100μm to 500 μm. The light-reflective film 6 has a thickness in a range of0.1 μm to 3.0 μm. The light source 9 including the encapsulating member5 (described later), can have a thickness in a range of 0.5 mm to 2.0mm.

Preferably, the light sources 9 are mounted on the substrate 8(described later) such that the light sources 9 can be driven separatelyfrom one another, and light control such as local dimming or highdynamic range (HDR) can be performed for each light source.

Light-Emitting Element 7

A known element can be used for the light-emitting element 7. Forexample, a light-emitting diode can preferably be used for thelight-emitting element. A light-emitting element that emits light havingappropriately selected wavelength can be used. Examples of a blue orgreen light-emitting element include a light-emitting element includinga nitride semiconductor. For a red light-emitting element, GaAlAs,AlInGaP, or the like can be used. Further, a semiconductorlight-emitting element made of a material other than the above materialscan also be used. The composition, emission color, size, and number ofthe light-emitting elements to be used can be selected appropriatelydepending on the purpose.

The light-emitting element 7 can be flip-chip mounted via bondingmembers 3 so as to straddle the gap between a pair of positive andnegative wiring layers 4A and 4B that are disposed on the upper surfaceof the substrate 8 as shown in FIG. 2A. The light-emitting element 7 canbe face-up mounted as well as flip-chip mounted. The bonding members 3are configured to fix the light-emitting element 7 to the substrate orconductor wiring. The bonding member 3 can be an insulating resin or anelectrically conductive member. For a flip-chip mounted light-emittingelement, an electrically conductive member is used as shown in FIG. 2A.Examples of the bonding members 3 include Au-containing alloys,Ag-containing alloys, Pd-containing alloys, In-containing alloys,Pb—Pd-containing alloys, Au—Ga-containing alloys, Au—Sn-containingalloys, Sn-containing alloys, Sn—Cu-containing alloys,Sn—Cu—Ag-containing alloys, Au—Ge-containing alloys, Au—Si-containingalloys, Al-containing alloys, Cu—In-containing alloys, and mixtures ofmetals and fluxes.

Encapsulating Member 5

The encapsulating member 5 covers the light-emitting element to protectagainst external environments and to optically control light exitingfrom the light-emitting element. The encapsulating member 5 is formed ofa light-transmissive material. Examples of the light-transmissivematerial include a light-transmissive resin such as an epoxy resin, asilicone resin, and a combination of these resins, and glass. Amongthese materials, a silicone resin is preferably used in consideration oflight resistance and ease of molding. The encapsulating member 5 cancontain a wavelength conversion material, light diffusing agent and/or acolorant. The wavelength conversion material can be a phosphor thatabsorbs light emitted from the light-emitting element to emit light thathas a different wavelength from the light emitted from thelight-emitting element. The diffusing agent diffuses light emitted fromthe light-emitting element. The colorant can be one corresponding to anemission color of the light-emitting element.

The phosphor, the diffuser, and the colorant known in the field of thedisclosure can be used.

The encapsulating member 5 can be directly in contact with the substrate8.

Viscosity of the encapsulating member 5 is adjusted to be able to beprinted or applied by using a dispenser, and can be cured by heattreatment and light irradiation. Examples of shapes of the encapsulatingmember 5 include a substantially hemispherical shape. The substantiallyhemispherical shape includes a vertically-long protruding shape in across-sectional view in which a length along the Z axis is longer than alength along the X axis in a cross-sectional view. The substantiallyhemispherical shape also includes a laterally-long protruding shape in across-sectional view in which a length along the X axis is longer than alength along the Z axis in a cross-sectional view.

The encapsulating member 5 can have a circular shape, and an oval shapein a top view.

The encapsulating member 5 can be disposed as an underfill 5 a betweenthe lower surface of the light-emitting element 7 and the upper surfaceof the substrate 8.

Substrate 8

The substrate 8 is a member on which the light sources 9 are disposed,and has the wiring layers 4A and 4B on the upper surface to supplyelectric power to the light source 9 (such as the light-emitting element7) as shown in FIG. 2A. Regions of the wiring layers 4A and 4B that arenot electrically connected is preferably covered with a covering member2.

The substrate 8 can be made of any material that can electricallyinsulate and separate at least a pair of the wiring layers 4A and 4B.Examples of the materials include ceramics, resins, and compositematerials. Examples of the ceramics include alumina, mullite,forsterite, glass ceramics, and nitride (for example, AlN) and carbide(for example, SiC) ceramics, and LTCC. Examples of resins includephenolic resins, epoxy resins, polyimide resins, BT resins,polyphthalamide (PPA), and polyethylene terephthalate (PET). Examples ofcomposite materials include mixture of the above-mentioned resins andinorganic fillers such as glass fiber, SiO₂, TiO₂ or Al₂O₃, glass fiberreinforced resins (for example, glass epoxy resins), and metalsubstrates configuring an insulating layer on a metal member.

The substrate 8 can have an appropriate thickness and can be a flexiblesubstrate that can be manufactured using a roll-to-roll manner or can bea rigid substrate. The rigid substrate can be a slim rigid substratethat is bendable.

The wiring layers 4A and 4B can be formed of electrically conductivemembers, and a material that is generally used for a wiring layer of acircuit board. A plated film, a light-reflective film or the like can beformed on a surface of the electrically conductive wiring.

The covering member 2 is preferably formed of an insulating material.Any materials described as examples for the substrate material can beused for the covering member 2. The covering member can be any of theabove-mentioned resins that contain a white filler and the like toinhibit leakage or absorption of light and to increase light extractionefficiency of the light source device.

Reflective Member 10

The reflective member 10 includes the one or more first walls 11 thatsurround a corresponding one of the light sources 9, and the one or moresecond walls 12.

The first walls 11 are preferably disposed such that each light source 9arranged on the substrate is located near the center (or the center ofgravity) of the first walls 11, more preferably at the center (or thecenter of gravity) of the first walls 11. The first walls 11 can have aframe shape of polygons such as quadrilaterals or hexagons, circles, andellipses in a plan view. Among these shapes, a quadrilateral grid asshown in FIG. 1A or a hexagonal grid as shown in FIG. 3C is preferable.Particularly, a square grid is more preferable. The first walls 11define, a plurality of regions, in other words, the first regions 11R,having a predetermined shape by the walls having the frame shape asdescribed above. The region that includes the light source 9 and issurrounded by the reflective member 10, in other words, an outline ofthe first region 11R that is defined by the first walls 11 can have ashape of a circle, an ellipse, a polygon such as a quadrilateral or ahexagon in a top view. Among these shapes, a polygon, particularly aquadrilateral is preferable. This configuration allows thelight-emitting region to be divided into a desired number of sectors bythe first walls 11 depending on the area of the light-emitting surfaceof the surface-emitting light source device. Hence, the light-emittingregions can be located in high density. The first regions 11R that aredefined by the first walls 11 are preferably defined regularly. Thenumber of the first regions 11R defined by the first walls 11 can be setdesirably and can be adjusted as required depending on an intended sizeof the light source device. Some of the first regions 11R can have adifferent size and/or shape, however, all of the first regions 11Rpreferably have the same size and shape.

In other words, in the reflective member 10, the first walls 11 arepreferably connected with each other and arranged in frame shapes suchthat the first regions 11R surrounding the respective light sources 9are regularly arranged, for example, vertically and laterally, incolumns and rows, or in a matrix shape.

The second walls 12 define one or more of, preferably a plurality ofregions having a predetermined shape, in other words, the second region12R and the third regions 13R. In the reflective member 10, the secondwalls 12 are disposed outside the first walls 11 and have an openingfacing outside the reflective member 10, that is, outside the lightsource device. In other words, the second walls 12 define the secondregion 12R and the third region 13R, each of which is only partiallysurrounded by the second walls 12. The opening herein can be opened in aportion of a height direction of the second walls 12, however,preferably fully opened in the height direction of the second walls 12.The term “outside of the first walls” or “on an outer side of the firstwalls” refers to outside the first walls near an outer periphery of thereflective member 10 in a plan view as shown in FIG. 1A. In the case inwhich the reflective member 10 has a through hole 32 inside an outermostperiphery in a plan view as shown in FIG. 3B, the term “outside of thefirst walls” or “on an outer side of the first walls” also refers to thethrough hole 32 sides of the first walls that are positioned near thethrough hole 32.

In other words, in the reflective member 10, the second walls 12 areconnected to the first walls 11 to constitute a portion of the frameoutside the first walls 11.

A region that is partially surrounded by or partially defined by thesecond walls 12 is referred to as the second region 12R or the thirdregion 13R. The second region 12R and the third region 13R have a shapein which a portion of the shape of the first region 11R is absent in aplan view, as compared to a complete shape of the first region 11R.Particularly, the second region 12R has an area that is no smaller thanhalf the area of the first region 11R surrounded by the first walls 11.The third region 13R has an area that is smaller than half the area ofthe first region 11R. In other words, the second region 12R has a regionthat corresponds to the center (or the center of gravity) of the firstregion 11R and that has an area no smaller than half the area of thefirst region 11R. Also in other words, the third region 13R does nothave a region that corresponds to the center (or the center of gravity)of the first region 11R and that has an area that is smaller than halfthe area of the first region 11R. In still other words, the secondregion 12R has a region that corresponds to the center (or the center ofgravity) of the first region 11R, while the third region 13R does nothave a region that corresponds to the center (or the center of gravity)of the first region 11R.

The one or more second regions 12R and the one or more third regions 13Rcan have planer shapes that can be set as appropriate depending on aplaner shape of the first region 11R, a planer shape of the reflectivemember 10, and display devices of instruments to which the light sourcedevice is installed, and the like. In the case in which the reflectivemember 10 includes a plurality of second regions 12R and a plurality ofthird regions 13R, the shape of the second and third regions can be thesame or can be partially or fully different from each other. This allowsthe light source device to have an irregular shape that can fit theshape of instruments and, therefore the light source device can bedownsized. As an examples of the shapes among various shapes, a regionis formed by cutting the single first region 11R (defined by the firstwalls 11) at an appropriate portion along a line that is parallel to oneof the sides (see N portions in FIGS. 1A, 3A through 3C).

As another example, a region is formed by cutting the single firstregion 11R (defined by the first walls 11) at an appropriate portionalong a line that is inclined at an appropriate angle with respect toone of the sides (see J, W, L portions in FIGS. 1A, 3A through 3C).

As still another example, a region is formed by cutting the single firstregion 11R (defined by the first walls 11) along a line and a curve asappropriate (see K portions in FIGS. 1A, 3A through 3C).

As still another example, a region is formed by cutting the single firstregion (defined 11R by the first walls 11) along an appropriate curve.

The light source 9 is disposed in the second region 12R and not disposedin the third region 13R. As described above, if the second region 12Rincludes a region that corresponds to the center (or the center ofgravity) of the first region 11R, the light source 9 is disposed at ornear the region that corresponds to the center (or the center ofgravity). In the case in which the second region 12R does not include aregion that corresponds to the center (or the center of gravity) of thefirst region 11R but have an area no smaller than half the area of thefirst region 11R, the light source 9 cannot be disposed.

The third regions 13R, which is partially surrounded by the second walls12 and does not include the light source 9, are disposed such that eachthird region 13R is not continued to each other in a vertical direction,a lateral direction, or an oblique direction (see J, W, K, N, Lportions, etc. in FIGS. 1A, 3A through 3B) as seen in a plan of thefigure. This configuration may inhibit to generate dark regions at anedge portion of the light source device in the case of using irregularshape of a reflective member, and effectively inhibit unevenness inluminance in the plane.

In a plan view, the reflective member 10 has a configuration in whichthe first walls 11 constitute parallel vertical sides or parallellateral sides (see Q portions in FIGS. 1A, 3A through 3C), while thesecond walls 12, the second regions 12R or the third regions 13Rconstitute sides that are inclined or curved with respect to thevertical or lateral sides defined by the first walls 11 or the firstregion 11R (see J, W, K, N, L portions, etc. in FIGS. 1A, 3A through3C). The inclination or curve herein can be appropriately set dependingon the size and arrangement of the light source 9, the application inwhich the light source device is used, and the like. That is, if theouter periphery of the reflective member 10 has parallel sides invertical and/or lateral directions (see Q portions in FIGS. 1A, 3Athrough 3C), the first walls 11 can be disposed to constitute theparallel sides, whereas the second walls 12 do not substantiallyconstitute the sides at the outer periphery of the reflective member.The second regions 12R or the third regions 13R constitute the peripheryof the reflective member 10 together with the first walls 11 (see J, W,K, N, L portions, etc. in FIGS. 1A, 3A through 3C).

The first walls 11 and the second walls 12 constitute boundaries ofadjacent regions and are preferably inclined, widening upward of thelight source 9 in a cross-sectional view. The angle of the walls (γ inFIG. 1D) is, for example, in a range of 45 degrees to 75 degrees.

The upper end of the first walls 11 and the second walls 12 can beplanar. However, at least two walls that surround adjacent regionspreferably form a ridge shape. In other words, as shown in FIG. 1A, avertical cross sectional shape of at least two walls configuring an apexis preferably an acute triangle, and more preferably an acute isoscelestriangle. The acute angle, i.e., the angle at the apex (a in FIG. 1D) ofthe acute triangle or the acute isosceles triangle is preferably in arange of, for example, 30 degrees to 90 degrees. Employing this range ofthe angle can reduce a space and region that are occupied by thereflective member 10, and decrease a height of the reflective member 10,to thereby allowing the light source device to be compact and slim.

The first walls 11 and/or the second walls 12 have a width (M portion inFIG. 1D) that can be appropriately set by the angle α and the angle γ ofthe first walls 11 and the second walls 12, and a height OD of thereflective member, which will be described later. This can downsize thelight source device.

The first walls 11 and the second walls 12 can be formed into variousshapes depending on the number and the position of the light sources 9arranged on the substrate 8 in a plan view. As an example of the shape,three of the first regions 11R and/or the second regions 12R and/or thethird regions 13R are disposed adjacent to one another and three apexesare positioned at one point (see FIG. 3C). As another example of ashape, four of the first regions 11R and/or the second regions 12Rand/or the third regions 13R are disposed adjacent to one another andfour apexes are positioned at one point as shown in FIG. 1A and otherdrawings. As still another example of a shape, six of the first regions11R and/or the second regions 12R and/or the third regions 13R aredisposed adjacent to one another and six apexes are collected at onepoint.

The first walls 11 and/or the second walls 12 have a pitch (P portion inFIG. 1B) that can be adjusted appropriately depending on a size andperformance of the light source to be used, and the like of the intendedlight source device. For example, the pitch can be in a range of 1 mm to50 mm, preferably 5 mm to 20 mm, more preferably 6 mm to 15 mm.

In addition, each of the reflective members 10 preferably has a bottomsurface 10 c. The bottom surface 10 c has a through hole at asubstantially center of the first region 11R. As shown in FIG. 1A andother drawings, the light source 9 is preferably disposed in the throughhole. The through hole has a shape and a size in which the whole of thelight source 9 is exposed, and preferably has an outer edge that islocated only near the light source 9. Accordingly, light emitted fromthe light source can be reflected on the bottom surface 10 c. Thisconfiguration may improve light extraction efficiency.

The height of the reflective member 10, that is, the height from a lowersurface of the bottom surface 10 c of the reflective member 10 to theapex of the first walls 11 and the second walls 12 (OD in FIG. 1D) ispreferably 8 mm or lower, more preferably in a range of 1 mm to 4 mm fora light source device with reduced height. This can make a wholebacklight unit including optical members such as a diffusion plate,which will be described later, have a relatively slim shape.

The reflective member 10 has a thickness in a range of, for example, 100μm to 300 μm.

The reflective member 10 is preferably disposed on or above thesubstrate 8. The lower surface of the bottom surface 10 c of thereflective member 10 is preferably fixed to the upper surface of thesubstrate 8. Particularly, the periphery of the through hole ispreferably fixed by using a light-reflective adhesive member to inhibitlight emitted by the light source 9 from being incident between thesubstrate 8 and the-reflective member 10. More preferably, thelight-reflective adhesive member is disposed, for example, in a ringshape along the outer edge of the through hole. The adhesive member caninclude a double-sided tape, a hot-melt type adhesive sheet, and a resinadhesive such as thermosetting resin or thermoplastic resin. Theadhesive member preferably has a high flame resistance. The reflectivemember 10 can be fixed on the substrate 8 using screws and the like.

The reflective member 10 has a light reflectivity, and effectivelyreflects light emitted from the light source 9 by the first walls 11,the second walls 12, and the bottom surface 10 c. Particularly, in thecase in which the first walls 11 and the second walls 12 are inclined asdescribed above, the light emitted from the light source 9 is projectedto the first walls 11 and the second walls 12 to be upwardly reflected.Also, even if non-lighting occurs in the adjacent first region 11Rand/or the adjacent second region 12R, a contrast ratio can beincreased, and light is more efficiently reflected upward.

The reflective member 10 can be formed of resins that contain reflectivematerials made of metal oxide particles such as titanium oxide, aluminumoxide, or silicon oxide. The reflective member 10 can also be formedsuch that a resin material that contains no reflective material isformed, and then, a reflective material or a reflective film is providedon the surface of the resin material. The reflective member 10preferably has a reflectance that is set to 70% or more with respect tothe light emitted from the light sources 9.

The reflective member 10 can be a rigid member, a flexible member, orcan partially include at least one of these members. The reflectivemember 10 can be a planer member constituting a planer surface, a memberconstituting a curved surface and the like, or a member having acombination of these members.

The reflective member 10 can be formed by various methods such asmolding methods using a mold and forming methods by photofabrication.Applicable molding methods using a mold include injection molding,extrusion molding, compression molding, vacuum forming, pressureforming, and press forming. For example, the reflective member 10 can beformed by vacuum forming using a reflective sheet made of PET and thelike to integrally form the bottom surface 10 c, the first walls 11, andthe second walls 12.

Other Members

Further, the light source device according to the present embodimentpreferably includes, as shown in FIGS. 1E and 1F, a diffusion plate 14and/or a diffusion sheet 22, a wavelength conversion sheet 23, a prismsheet 24, a polarizing sheet 25, an exterior substrate 27 (an exteriorsubstrate member) that has a reflective wall surrounding an outerperiphery of the substrate, and a covering substrate 26 (a coveringsubstrate member) that has a reflective wall surrounding an outerperiphery of the reflective member. The above members can beappropriately layered via an adhesive layer and/or the reflective layers28, 29, 31, and the like. In the case in which such a light sourcedevice is provided with a liquid crystal panel or the like furtherthereon to obtain a surface-emitting light source device that is used asa light source for a direct backlight device. The above optical memberscan be layered in an appropriate order.

Diffusion Plate 14 and/or Diffusion Sheet 22

The diffusion plate 14 and/or the diffusion sheet 22 (hereinafter bothreferred to simply as the diffusion plate 14) are a member to diffuseand transmit incident light. Preferably, a single diffusion plate 14 isdisposed above the light sources 9. The diffusion plate 14 is preferablydisposed such that the diffusion plate 14 is substantially in contactwith the apex of the first walls 11 and the second walls 12. Thediffusion plate 14 is preferably a planer board-like member and can haveirregularities on a surface thereof. The diffusion plate 14 ispreferably disposed substantially parallel to the substrate 8. Thediffusion plate 14 can be constituted of a material that is less likelyto absorb visible light, for example, a polycarbonate resin, apolystyrene resin, an acrylic resin, or a polyethylene resin. Fordiffusing incident light, the diffusion plate 14 can have irregularitieson the surface, or a material having a refractive index different fromthe refractive index of the diffusion plate 14 can be dispersed in thediffusion plate 14.

The irregularities can have a size in a range of, for example, 0.01 mmto 0.1 mm.

The material having a refractive index different from the refractiveindex of the diffusion plate 14 can be selected from, for example,polycarbonate resins, and acrylic resins.

The diffusion plate 14 can have a thickness and degree of diffusion thatare appropriately set. A commercially available component, such as alight diffusion sheet or a diffuser film can be used. For example, thediffusion plate 14 can have a thickness in a range of 1 mm to 2 mm.

Supposing that the first walls 11 and/or the second walls 12 of thereflective member 10 defines a pitch P, the diffusion plate 14 ispreferably disposed such that a distance between the diffusion plate andthe light source (i.e., a height OD) is preferably 0.3 P or lower, morepreferably 0.25 P or lower. As shown in FIG. 1D, the height OD hereinindicates from an outermost surface of the substrate 8 to the lowersurface of the diffusion plate 14, in other words, from the outer mostsurface of the covering member 2, wiring layers 4A and 4B, or the liketo the lower surface of the diffusion plate 14 when the substrate 8includes such a member as the outermost surface. In another view, forexample, as shown in FIG. 2A, the diffusion plate 14 is preferablydisposed at a distance in a range of 1.5 mm to 5 mm, more preferably ina range of 2 mm to 3 mm, from the upper surface of the bottom surface 10c of the reflective member 10.

The diffusion plate 14 can have a reflective portion on the uppersurface and/or the lower surface at a region above or preferablydirectly above the light source. The distance between the diffusionplate 14 and the light source 9 is the shortest at the region above thelight source, particularly directly above the light source. Hence,luminance in this region is the highest. The shorter the distancebetween the diffusion plate 14 and the light source 9 is, the moreunevenness in luminance appears between a region that does not includethe light source 9 and the region that is directly above the lightsource 9. By disposing the reflective portion on a surface of thediffusion plate 14, a portion of light emitted from the light source 9having high directivity is reflected back toward the light source 9.Hence, unevenness in luminance can be reduced.

The diffusion plate 14 can have another reflective portion on the uppersurface and/or the lower surface at a region above or preferablydirectly above the apex of the first walls 11 and/or the second walls12.

In the case of local dimming of the light sources 9, the apex of thefirst walls 11 and/or the second walls 12 serves as a border regionbetween a non-lighting region and a lighting region. The reflectiveportion disposed at the border region can inhibit light leakage from thelighting region to the non-lighting region and can reflect lighttraveling to the non-lighting region upward the light source 9.

The reflective portion can be made of a material containing alight-reflective material. Examples of the materials include resinsand/or organic solvents containing the light-reflective material.Examples of the light-reflective materials include metal oxide particlessuch as titanium oxide, aluminum oxide, or silicon oxide. The resins andthe organic solvents can be appropriately selected according to themetal oxide particles to be used and required properties for lightsource devices to be manufactured. Among these resins, a lighttransmissive resin curable with light is preferably used, for example, aresin containing an acrylate resin or an epoxy resin as a maincomponent.

The reflective portion can be formed into various predetermined shapesor patterns such as stripes or islands. The reflective portion can beformed by a known method in the art such as printing, ink-jetting, orspraying.

The reflective portion has a thickness in a range of, for example, 10 μmto 100 μm.

Wavelength Conversion Sheet 23

The wavelength conversion sheet 23 can be disposed facing either theupper surface or the lower surface of the diffusion plate 14, however,as shown in FIGS. 1E and 1F, preferably facing the upper surface of thediffusion plate 14 and/or the diffusion sheet 22. The wavelengthconversion sheet 23 absorbs a portion of light emitted from the lightsource 9 to emit light having a different wavelength from the lightemitted from the light source 9. For example, the wavelength conversionsheet 23 absorbs a portion of blue light emitted from the light source 9to emit yellow, green, and/or red lights that are mixed to form whitelight. Hence, a light source device that emits white light can beobtained. The wavelength conversion sheet 23 is spaced apart from alight-emitting element of the light source 9. This configuration allowsfor use of phosphors and the like having low heat or low lightresistance, which may be difficult to use near the light-emittingelement. This may increase performance of the light source device as abacklight. The wavelength conversion sheet 23 has a sheet-like shape ora layered shape and contains the above-mentioned phosphors and the like.

Prism Sheet 24

The prism sheet 24 has a surface on which prisms are elongated along apredetermined direction. For example, assuming the prism sheet 24 istwo-dimensional having an x axis and a y axis perpendicular to the xaxis, the prism sheet 24 can be configured by layering a sheet havingprisms elongated along the x axis and a sheet having prisms elongatedalong the y axis. The prism sheet can refract light incident fromvarious directions toward the display panel that faces the light sourcedevice. This allows light emitted from the light-emitting surface of thelight source device to travel mainly in a direction perpendicular to anupper surface, and increases luminance viewed from a front face of thelight source device.

Polarizing Sheet 25

The polarizing sheet 25 selectively transmits light polarized in apolarization direction that matches a polarization direction of apolarizer disposed at the backlight side of a display panel such as aliquid crystal display panel, and reflects the light polarized in adirection perpendicular to the polarization direction toward the prismsheet 24. A portion of the polarized light returning back from thepolarizing sheet 25 is reflected again by the prism sheet 24, thewavelength conversion sheet 23, and the diffusion plate 14. At thistime, the polarization direction of the portion of the light changes,for example, the portion of the light is polarized in the polarizationdirection of the polarizer of the liquid crystal display panel, isincident on the polarizing sheet 25 again, and is emitted to the displaypanel. Accordingly, a polarization direction of light emitted from thelight source device is aligned and light polarized in a directioneffective for increasing luminance of the display panel can be emittedwith high efficiency. Commercially available optical members for use ina backlight can be used for the polarizing sheet 25, the prism sheet 24,and the like.

Covering Substrate 26 and/or Exterior Substrate 27, Adhesive Layerand/or Reflective Layers 28, 29, and 31

The covering substrate 26 has the reflective wall surrounding the outerperiphery of the reflective member 10 and covers the optical memberssuch as the reflective member 10 and the above-mentioned diffusion plate14 by fixing or supporting the upper outer edges of these opticalmembers.

The exterior substrate 27 has the reflective wall surrounding the outerperiphery of the substrate 8 and covers from a rear surface of thesubstrate 8.

By bringing in contact with or engaging the reflective walls of thecovering substrate 26 and the exterior substrate 27 each other, lightemitted from the light-emitting device is inhibited from leaking out ofthe reflective walls, that is, inhibited from leaking out of the lightsource device. This may improve luminance on the light-emitting surface.

The covering substrate 26 and the exterior substrate 27 can be made ofmaterials that can reflect light emitted from the light-emitting device,such as resins containing a light-reflective material, metals, orceramics.

The adhesive layer and the reflective layer can be made of materialsthat can bond upper and lower members and can reflect direct light orindirect light emitted from the light-emitting device. For example, adouble-sided tape, a hot-melt type adhesive sheet, and a resin adhesivesuch as thermosetting resin or thermoplastic resin, can be used.

The light source devices according to the present disclosure areapplicable to various light source devices such as a light source of thebacklight of display devices, a lighting device, a light source ofin-vehicle instruments.

The invention claimed is:
 1. A light source device comprising: aplurality of light sources; a substrate on which the light sources arearranged; and a reflective member arranged on the substrate via anadhesive member, the reflective member defining a plurality of throughholes, the reflective member including first walls defining a firstregion surrounded by the first walls in a plan view, and second wallslocated on an outer side of the first walls and defining a second regionhaving an opening facing outside of the reflective member in the planview, an area of the second region being smaller than an area of thefirst region, wherein the light sources are respectively disposed insidethe through holes in a plan view, and the adhesive member islight-reflective.
 2. The light source device according to claim 1,wherein the adhesive member is arranged in a periphery of each of thethrough holes.
 3. The light source device according to claim 1, whereinthe adhesive member includes a double-sided tape, an adhesive sheet, ora resin adhesive.
 4. The light source device according to claim 1,wherein the reflective member is made of polyethylene terephthalate. 5.The light source device according to claim 1, further comprising atleast one member selected from a group consisting of a diffusion plate,a diffusion sheet, a wavelength conversion sheet configured to convertlight emitted from at least one of the light sources to light having adifferent wavelength, a prism sheet, and a polarizing sheet.
 6. Thelight source device according to claim 1, wherein each of the lightsources includes a light-emitting element.
 7. The light source deviceaccording to claim 1, wherein each of the light sources includes alight-emitting element and a light-transmissive encapsulating membercovering the light-emitting element.
 8. The light source deviceaccording to claim 6, wherein each of the light sources further includesa light-reflective film arranged on an upper surface of thelight-emitting element.
 9. The light source device according to claim 7,wherein each of the light sources further includes a light-reflectivefilm arranged on an upper surface of the light-emitting element.
 10. Thelight source device according to claim 1, wherein the substrate includesa wiring layer electrically connected to the light sources.
 11. Thelight source device according to claim 1, wherein the first walls andthe second walls are spaced apart from the through holes.